Oil and gas wells can be treated by fracking (hydraulic fracturing) and chemical injections to increase production. The fracking process occurs after a bore hole has been formed through a formation, and is sometimes referred to as completing the well. Fracking forms fractures in a formation that are typically oriented parallel to the maximum induced stresses in the formation and perpendicular to the minimum induced stresses in the formation. Following (or during) fracking, a granular proppant material can be injected into the fractures to hold them open. The fractures provide low resistance flow paths through the formation into the well liner. Chemical injections can also be used separately, or in combination with fracking, to increase flow capacity by dissolving materials or changing formation properties.
One fracking method involves drilling a horizontal well bore, and inserting a liner into the well bore. The annulus between the liner and the well bore is then filled with cement. The liner is then perforated in sections of typically from 100 to 1000 feet using a perforating device. In addition, a packer on a coiled tubing string can be placed at the lower end of the segment and actuated to establish a hydraulic seal. Hydraulic fracturing can then be performed in the sealed perforated segment. The packer can then be released and moved to repeat the process.
This prior art fracking method is expensive as the well bore is relatively large and the liner must be made of high strength steel and cemented in place. In addition, in non-cemented liners, the packers have a limited life expectancy and a low reliability. Also due to the complexity of the method, only a limited number of stages can be performed. For example, a 4000 feet horizontal well bore can typically only be treated in 10 stages of 400 feet with each stage having 3-4 perforated zones. Another problem is that the high pressures needed for hydraulic fracturing can damage cemented liners.
The present disclosure is directed to a method and system for fracking and completing wells that is better, faster and cheaper than prior art methods and systems. In particular, lower cost materials are used, and the downhole perforating operation and external liner pockets are eliminated. Further, more stages can be performed, more fractures can be formed, more proppant can be injected and higher flow rates can be achieved.
However, the foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.